[pulseaudio-discuss] system-wide daemon

[Lennart Poettering]

On Wed, 10.02.10 07:14, David Henningsson (launchpad.web at epost.diwic.se) wrote:

> But printers are more of a system-wide resource, and for some use cases,
> so is the soundcard. 

This is nonsense. I am not sure how your ears are constructed, but on
a multiseat system if you want to share a soundcard between two seats,
where would you put the speakers so that the two users have the same
distance from L and R and they are on the left and the right side? I
mean, those users would have to sit on top of each other or detachable
ears or something.

We discussed this with a couple of folks long time ago, and decided
that some reasources are per-seat resources, and should be configured
like that. Those devices are keyboards, mice, screens, sound cards,
webcams and a couple of others. the UDEV_ACL=1 property in the udev
tree marks most of them. This discussion was mostly done on the udev
level btw, it is only indirectly related to PA.

Now, in some non-standard cases it might make sense to have the access
rules deviate from this default, but those are the exceptions, not the
common cases. And that means that you configure it that way, but the
default will be the safe, common case, not the dangerous uncommon
case.

So, how do you reconfigure access to audio devices like that? More
recent udev versions know an "audio" group. Just make yourself a
member of that, and you'll have access regardless of the current
console user. Or alternatively use some udev rules to patch the
device access differently.

BTW, I really do not know why I am even responding, this has been
answered before and before. Do you know this Google thing? It's kinda
cool, you should try it.

> And then, sharing makes sense. If another user is
> allowed to print a document while I'm logged in, why shouldn't he be
> able to play a sound? So would then the solution be to run PA as a
> system-wide daemon, and possibly assign soundcards to it via udev?

Right, allow every user to listen into all voip calls, and to fake
output. Lemme guess, you disable access control to your X11 screen too?

> And the way ck/udev tells PA what devices it can use, is through device
> permissions?

PA gets the device access rights directly from the /dev tree. It
doesn't query CK or udev for those. We try to keep our stacks thin.

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net
http://0pointer.net/lennart/           GnuPG 0x1A015CC4